This relates generally to threshold switching memory cells, such as phase change memory cells.
A threshold switch with a variable threshold voltage, such as a phase change memory, has a threshold voltage that determines the state of the memory. The threshold voltage may be varied by programming.
Thus, phase change memories may have a set or lower resistance state and a reset or higher resistance state. A cell may switch between set and reset states, for example, in response to programming that applied sufficient current to change the crystallographic structure of the phase change material.
Generally, cells are read by measuring the amount of current. The set cell passes more current and the reset cell passes less current. Thus, the current consumption of the cell in the set state read operation may be relatively high. Basically, the static current is supplied for the duration of the read operation in order to keep the cell in the on state.